1. Field of the Invention
This invention generally relates to beverage apparatus of the type having a liquid holding tank from which liquid, either water used to make a beverage or the beverage itself is held and more particularly such a beverage apparatus in which electrical power must be switched to an operating apparatus, such as a heat element or cooling device, by an electronic switching device, such as a triac or the like.
2. Discussion of the Prior Art
Commercial coffee brewers and tea brewers of the type that have a tank of heater water that is selectively passed through a brew basket containing ground coffee, or tea leaves or the like from which the beverage is brewed are well know. Reference may be made to U.S. Pat. Nos. 6,148,717 issued Nov. 21, 2000 to Lassota for “Beverage Maker with Intermittent Beverage Liquid Dispenser and Apparatus and Method for Uniform Contact of Brew Ingredient with Brew”; 5,331,885 issued Jul. 26, 1994 to Lassota for “Semiautomatic Beverage Maker and Method”; 5,000,082 issued Mar. 19, 1991, to Lassota for “Beverage Maker and Method of Making Beverage”; 5,943,944 issued Aug. 31, 1999, for “Brewing System with Hot Water Urn Flushing Apparatus”; and 6,044,753 issued Apr. 4, 2000, to Lassota for “Brwing System with Movable Dispenser Urn Mounting Apparatus and Method”. In such brewers, an electrical heating element within the tank is connected to a source of electrical power through an electrical relay with mercury displacement heating element contactors. A problem with such contactors is the presence of the mercury that is potentially injurious to persons if they should come into direct contact with it due to breakage of mercury containment during use and which thus require special disposal procedures when the contactors are replaced or when the brewers themselves are discarded.
Accordingly, it is known to replace such contactors with electronic switches, such as triacs. A temperature sensor senses the temperature of the water in the hot water tank and when the sensed temperature decreases beneath a preselected temperature, a controller triggers the triacs into a conductive state. When the sensed temperature reaches another preselected temperature, the controller turns off the triac and the water is again allowed to cool. In many brewers, cold tap water from a public source at room temperature or colder is being added to the hot water tank while hot water is being drawing out of the tank to make the beverage, and thus the temperature can drop substantially beneath the preselected minimum temperature in a short time. A new brew cycle cannot be started until the temperature of the water is again raised to the preselected maximum temperature. It is therefore desired to raise the temperature to the maximum temperature as quickly as possible. Accordingly, it is necessary to pass relatively high quantities of electrical power through the triacs during the heating cycle.
Because of the nature semiconductors substantial heat is generated within the triacs during conduction when high power is being applied through the triac to the heating element. If the triac overheats beyond a certain level, it may be damaged and malfunction or cease to switch entirely. If the triac shorts out, then power may be continuously be applied to the hot water element and overheat the water beyond the preselected maximum temperature. In order to reduce this overheating of the triac it is known to provide the triac with a radiating heat sink that radiates heat into the atmosphere. Since the interior of the housings for the brewers are generally hotter than the room within which they are located it is known to mount the radiating heat sink spaced from the hot water tank and even on the outside of the housing. Because air is not highly heat conductive, and may, in fact, be considered an insulator, the heat sinks are relatively large, take up substantial space and are unsightly. Generally, the triac is in thermal contact with the radiating heat sink that, in turn, is in radiating heat contact with the atmosphere.
Such electrical power switches may also be found in hot tea and iced tea makers and also in beverage dispensers in general in which the beverage is heated, cooled, stirred or otherwise operated on by apparatus requiring substantial quantities of electrical power